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1 ## Copyright (C) 1996 Auburn University. All rights reserved. |
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2 ## |
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3 ## This file is part of Octave. |
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4 ## |
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5 ## Octave is free software; you can redistribute it and/or modify it |
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6 ## under the terms of the GNU General Public License as published by the |
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7 ## Free Software Foundation; either version 2, or (at your option) any |
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8 ## later version. |
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9 ## |
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10 ## Octave is distributed in the hope that it will be useful, but WITHOUT |
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11 ## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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12 ## FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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13 ## for more details. |
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14 ## |
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15 ## You should have received a copy of the GNU General Public License |
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16 ## along with Octave; see the file COPYING. If not, write to the Free |
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17 ## Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
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18 ## 02110-1301 USA. |
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19 |
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20 ## -*- texinfo -*- |
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21 ## @deftypefn {Function File} {[@var{y}, @var{t}] =} step (@var{sys}, @var{inp}, @var{tstop}, @var{n}) |
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22 ## Step response for a linear system. |
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23 ## The system can be discrete or multivariable (or both). |
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24 ## If no output arguments are specified, @code{step} |
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25 ## produces a plot or the step response data for system @var{sys}. |
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26 ## |
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27 ## @strong{Inputs} |
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28 ## @table @var |
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29 ## @item sys |
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30 ## System data structure. |
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31 ## @item inp |
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32 ## Index of input being excited |
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33 ## @item tstop |
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34 ## The argument @var{tstop} (scalar value) denotes the time when the |
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35 ## simulation should end. |
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36 ## @item n |
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37 ## the number of data values. |
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38 ## |
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39 ## Both parameters @var{tstop} and @var{n} can be omitted and will be |
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40 ## computed from the eigenvalues of the A Matrix. |
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41 ## @end table |
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42 ## @strong{Outputs} |
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43 ## @table @var |
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44 ## @item y |
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45 ## Values of the step response. |
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46 ## @item t |
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47 ## Times of the step response. |
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48 ## @end table |
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49 ## |
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50 ## When invoked with the output parameter @var{y} the plot is not displayed. |
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51 ## @end deftypefn |
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52 ## |
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53 ## @seealso{impulse and __stepimp__} |
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54 |
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55 ## Author: Kai P. Mueller <mueller@ifr.ing.tu-bs.de> |
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56 ## Created: September 30, 1997 |
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57 ## based on lsim.m of Scottedward Hodel |
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58 |
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59 function [y, t] = step (sys, inp, tstop, n) |
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60 |
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61 if ((nargin < 1) || (nargin > 4)) |
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62 usage ("[y, u] = step(sys, inp, tstop, n)"); |
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63 endif |
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64 |
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65 if (nargout > 2) |
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66 usage ("[y, u] = step (sys, inp, tstop, n)"); |
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67 endif |
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68 |
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69 if (! isstruct (sys)) |
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70 error ("step: sys must be a system data structure."); |
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71 endif |
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72 |
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73 if (nargout == 0) |
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74 switch (nargin) |
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75 case (1) |
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76 __stepimp__ (1, sys); |
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77 case (2) |
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78 __stepimp__ (1, sys, inp); |
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79 case (3) |
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80 __stepimp__ (1, sys, inp, tstop); |
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81 case (4) |
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82 __stepimp__ (1, sys, inp, tstop, n); |
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83 endswitch |
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84 else |
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85 switch (nargin) |
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86 case (1) |
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87 [y, t] = __stepimp__ (1, sys); |
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88 case (2) |
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89 [y, t] = __stepimp__ (1, sys, inp); |
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90 case (3) |
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91 [y, t] = __stepimp__ (1, sys, inp, tstop); |
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92 case (4) |
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93 [y, t] = __stepimp__ (1, sys, inp, tstop, n); |
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94 endswitch |
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95 endif |
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96 |
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97 endfunction |
